This invention relates to vehicles that are convertible between two-wheel and four-wheel drive and more particularly to a mechanism that connects and disconnects front axles from the front wheels.
Drive line connection to the front wheels is particularly distinguished from that of the rear wheels due to the front wheels also functioning as turning wheels. To achieve turning of the front wheels, the wheel hubs are rotatably mounted to a steering knuckle which is pivotally mounted to the fixed frame of the vehicle. The steering knuckle of the two front wheels are tied together by tie rods and the tie rods are engaged by a control mechanism that is manipulated by the vehicle""s driver to direct the vehicle in a desired direction.
To achieve front wheel drive, a drive line has to be connected to the front wheels without impairing the turning capability of the front wheels. This is accomplished by the provision of a drive line extended to a front end differential from which axles are laterally extended to a bell form or bell of a continuous velocity joint at the inboard side of the knuckle. The bell form which is rotatably driven by the front axle is also pivotal about the same axis as the steering knuckle. Thus, connection of the bell form with the wheel will produce driving of the wheel while also enabling the wheel and bell form to be turned via manipulation of the steering or tie rod.
It is the connection between the bell form and the front wheels to which the present invention is directed.
A prior construction for obtaining this connection included a stub-axle formed integral with the bell form, the stub-axle extended through the knuckle with bearings between the knuckle and stub-axle supporting the axle and maintaining axial alignment of the stub-axle. The stub-axle continued through the wheel hub where it was rotatably fixed (spline fit) to the wheel hub. The end of the stub-axle protruded through the wheel hub which end was threaded and a nut secured to the threaded end to axially secure the stub-axle to the wheel hub. Another prior construction included a spindle integral with the wheel hub and extended inwardly through the knuckle where it was rotatably supported by bearings. A stub-axle (again integral with the bell form) extended through the spindle and wheel hub. The stub-axle was fixed rotatively to the wheel hub by splines and a protruded end received a lock nut to secure the wheel hub and stub-axle together. That it will be appreciated that the components of the wheel end assembly including the CV joint, the stub axle, the knuckle and the wheel hub are all coupled in a desired relation (for axial and radial rotation).
It is desirable for many applications to convert the front wheels from driven (four-wheel drive) to non-driven (two-wheel drive). This is accomplished for the above structures by providing additional bearing support between the stub-axle and wheel hub. A clutch ring having splines that couple with both the wheel hub and stub-axle is selectively axially moved (automatically or manually) to couple and uncouple the wheel hub and axle to accomplish conversion between four-wheel and two-wheel drive.
A further development occurred for the convertible versions where the wheel hub is provided with a spindle that is bearing supported in the knuckle. The stub-axle is extended into but not through the spindle and wheel hub and bearing supported therein, the stub-axle being axially secured to the spindle to secure the entire assembly together. Rotative engagement of the bell form to the wheel hub is accomplished by clutch ring engagement between the bell form and the spindle at the inboard end of the spindle. (See U.S. Pat. No. 5,740,895).
The next development of wheel end assembly was the elimination of the stub-axle. In this later version, the bell form and wheel hub spindle are locked together for common rotation and the combination is bearing mounted to the knuckle in a manner that prevents axial movement. (See U.S. Pat. Nos. 5,853,250, 6,012,986 and 6,022,275) The latest development does not provide for selective engagement/disengagement for conversion between two-wheel and four-wheel drive. Accordingly, it is an objective of the present invention to provide front wheel drive to a wheel end assembly that eliminates the necessity of the stub-axle while maintaining the advantage of the integrated wheel end system of the ""895 patent (in providing selective coupling of the wheel hub to the bell form).
In the present invention, there are two separate bearing mounts, one for the wheel hub/spindle assembly, and the other for the bell form assembly. The bearings are mounted so as to provide rotative motion as between both of these components and the knuckle, and to enable relative rotation as between the wheel hub/spindle assembly and bell form assembly. The bearings are assembled to the structure to prevent relative axial movement. A coupling mechanism selectively connects or disconnects the wheel hub and spindle with the bell form.